Process for the electrolysis of alkali chlorids.



H. VAN HASSELT. PRUCESS FOB THE yELEGTROLYSIS 0F ALKAL! CHLORIDS. APELICATION FILED 001.12, 1916.

1,359,683 Patented Mar. 19, 1918.

2 SHEETS-SHEET l.

R. VAN HASSELT. PROCESS FOR THE ELEcTRoLvsls 0F ALKALI cHLoRlDs.

APPLICATION HLED OCT. l2, 1916.

Patented Mar. 19, 19l8.

2 SHEETS-SHEET 2.

Subject of eeieeeiep coil? we Heeemm, one 'ce Application le cto'be 3.2, Serial '25,253.

useful :improvements in Processes for the Electrolysis of Alkali Chiois, of which the following is e epecication.

It hee been proposed in connection with eiectioiytic cells having e horizontal porous diaphragm to restrict the impovei'ishment of the electrolyte in the anode compartment by providing ay seit chemloei` adje-cent to that compartment and communicating with' it nem.1 the bottom., it is clear that euch en arrangement een cio ittie goed, since the circu'itton necessary to diesoive the seit emi to bring it into the anode compartment Where there is poverty of seit, namely in the upper pert of the compartment, must be 'cy wey of the narrow bottom communication just mentioned. "She object of pee-vicine; such e chamber wes not eo much to produce e circuieton in the anode compartment e to reinforce the layer ci? eeettcolyte immecii atey above the diaphragm. 4

it has also been propose to piace the sait in the anode compaitment itse En tie case, however, the Seit may cause much resistence to the current and the iiquici may icecome setureted with seit which may cryete`llize in the diaphragm, choking the etter anni increasing its resistance.

Accoringito the pfeeent invention the sait chamber is etz-ranged in such e menne? thet Vits object-the maintenance of a ien-tage proportion oit' sait in 'the :mode com mtn ment-is ui attained Without any getti mentei secco eey e'ects.

The seit chamber ie seperated from the oeil and is usec' eso for expeiing the choric from the anode iiquici end for heating tie iiquic. Foi this. purpose the mode iiqui.

coriteinin chlorin ows out of the upper part of t e enode compartment through e wide ipe into the upper part of the covece sait c amber. The latter consists prefe'ebiy of e long' chamber having near its bottom grating of chlorin, proof meteriei upon which the seit is placed. l"Unc'er this grating steam pipes are piovided to heet thev sointion. The outlet for the solution ie aise imde the grating. The chamber is coveied "oy e iid having e tube for escape or Witifidfewei of the chioiin. Tice solution settlement with eelt, and es it is also heated 'from te low, the chic setureteci cii, L-- eee eci weiied .tion flows imm the iowe1 peet oi the cemoeij Wi'iepce it returns to the iowe part of tice erectie oompe'tment, peereciy the tiiefeo opposite the outioiin This eppemtos makes it possible to coun tem'ct neeiy comp'etey the i Qpcveiisiriment t e seme time it o the quantity liquid e into "t v5 during; the

of the anode iiqui and n t t pemits' accurate edjustme end the compc-eitioii of the the :mode competment. u creuieticn of the motie uic it is possicie to edd such quantity ci iiyro-chioiid acid as is neceeseij/ to convert any iiypociiorite 'which may be 'etcmed into NM. ceci Cia, or to peuteiize 'the Ne 'that may pese thiough the diapiuaggm into anode compactment. Secondly, the eetuifeted anode iquid rete-ams iee f .f the emotie co hypccho Y sary o. iiquict m si" 'the poort which pessee thiougii the iiicpiilagm xriey be mede e co ,ve-nient piece iXi-the cir cuiatiop. the anote iiquid; peeiepiy efte' the iettei' imc ieii't Seit chamber. if?outhijf5 the veocity of circuietion emi tileiefoi'e tile meen compoeitioii ci the iiogud in the anode compertment mey ce contoiied by en iiseited cicuietiii ou ipf Fifthiy, the composition ci? l, miti iowiiig into the epoe competment can i e cjiieted. if, e) in ceder to tice diaphragm 'for it pipi/'ee neces pievent cyeteliieetion in that eoiction eiiouifi V"cot be Saturated when it were the motie comp itmet, tiieie may 'be ecimed to the -ifeetiin'f Solution in piece of e, setu'eted solution :L more ci: ieee ciiiuted one. Silithi'y, one may keep the anode iiqui Vey high t j, ere,ture, in e Simpiey wey than ie othefv'ec pcssibe, be cause the heating is not eppiied Within the imode compartment, but cxtei'ioriy thereof. Swcnthiya it ie poseigie to filter the iiquigi before cntei's the emotie comporm'xent, :toi exempe means ci :t iitei in the sait cham'bei. iin the lattei cese is nfotcrebie to boii o the chioiciiz in :L chicche? sepeiate from that for setuetipg i li seit.

The invention is iiiuetieteci by tno www..

penypp; tfiiewinge. l'gme i e vertice section o.l e ceii emi e' teeiiiiw c: foei', the

Section 'being teken on time @#D, 3; F g. 2 :showe in eicvzitlon 1 eelt chemoei and at eide View of the feeding ciiembci anni cell 5 2 -is a feeding apparatus or chamber covered with a glass bell 10, into the center. of which 4apparatus the salt solution is fed by an overflowing pipe 9 in which there may be an areometer and a thermometer for controlling the composition and temperature of the inflowing` liquid. 11 isa circulating pump of any suitable construction; 12 is a pipe for admission of vfresh solution. 3 is the salt chamber having a chlorin outlet 13, a grating 14 upon which the salt is placed and heating coils 15.; 16 is the pipe for the overflowingfanode liquid.l and the chlorin, and 17 is thepipe for returnin the saturated solution to the pump vand t ence to the feeding chamber and cell. The cathode liquidis discharged in well-known manner by a vertical pipe 27, (Fig. 1) which leadsr from the bottom of the cell 1 into an overflow vessel 28, said pipe 27 having a lbranch 29. through which the hydrogen escapes. The branch pipe 29v is immersed-in the liquid contained in a tank 80, the extent of such immersion being preferably regulatable in order to regulate the pressure in the cathode compartment, which pressure controls the rate oflflow of liquid through the diaphragm, and,

therefore, the strength of the resulting alkali.

In Figs. 4 and 5 the salt chamber acomprises two compartments. It has coils' 18, a.

chlorin outlet 19, an outflow 2O at the lower part of one compartment and an inflow 21 to the second compartment at the same height asl the inlet into the first-compartment. A conduit 22 constructedin the first compartment connects the outflow 20 with the iniow 21'; a perforated basket 23 contains the and .8 the liquid flows from the anode compartment to the salt chamber 3 where it is heated and at the same time saturated with salt. The chlorin escapes at 13, the saturated solution through the pipe 1:7. The pump 11 forwards it into the bell 10. Between the belll and the salt chamber is arranged thesupply pipe 12 through which is added fresh solution, more or less concentrated, according to the strength shown by the solution inthe bell. In the cell the height of the liquid must be visible which is attained most simply by making pipe 16 of lass, or by providing a sightl glass. The

aster the circulation, the higher the tem- Langages perature and concentration in .the anode compartment. The addition of fresh solution at 12 must correspond with the quantity of liquid passing through the diap hragm, augmented by the loss by evaporation.

In Figs. 4vand 5 the chlorin is expelled before the solution is saturated with salt. In this case 4one may use the salt obtained during the evaporation of lthe causticv lyes, which salt 'is more or lessalkaline, so that theliquid becomesalkaline and impurities are precipitated which must be removed by filtration. In this case it is advisable'to add the fresh solution to the salt chamber itself in order to 'filter it also.` Before returning the salt solution to the anodevcompartment, preferably a little hydrochloric acid is added to neutralize the alkaline reaction; at the same time care may be taken that the solution is not so far saturated that crystallization in the diaphragm is to be feared.

The foregoing descriptionshows that there is movement in the anode compartment in both -a horizontal and a vertical direction, besides the descent of: a'part of thel liquid through the diaphragm. The heavier, chlorin-free,' inliowing liquid spreadsitself above the diaphragm, flows upward along the anodes, becoming a little impoverished and saturated with chlorin, and leaves the cell in this condition. Care must be taken that the movement of the liquid in the anode compartment does not yenhance mechanical diffusion of cathode liquid through the should be suiiiciently thick and homogenediaphragm. To prevent this, the diaphragm ous. Preferably a rather thick, yet porous diaphragm of low resistance is selected. A

thin diaphragm may also be used, protected by a layer of acoarse-grained materialor the like Several cells may be connected with a sinl gle salt chamber.

What I claim is': Y

1. The herein-described process for the electrolysis of alkali chlorids in a cell containing a horizontal diaphragm, consisting in passing the anode liquid, in a slightly impoverished condition, from the upper part of the anode compartment of the cell containing the diaphragm, to a salt chamber removed from the cell; heating said liquid in the salt chamber to eXpel the chlorin, re-

'saturating it therein with salt; and returning the re-saturated liquid to the lower' part of said compartment.

2. The herein-described process for the electrolysis of alkali chlorids in a cell containing a horizontal diaphragm, consisting in passing the anode liquid, in a slightly impoverished condition, from the upper part of the anode compartment of the cell containing the diaphragm, to a salt chamber removed from'the cell; heating said liquid in the salt chamber toeXpel the chlorin; resaturating it therein with salt after the chlorin has been expelled; and returning the resaturated liquid to the lower part ofsaid compartment.

3. The herein-described process for the electrolysis of alkali chlorids in a cell containing a horizontal diaphragm, consisting in mechanically cirnulating the anode liquid from the upper part of the anode compartment of the cell containing the diaphragm, to a salt chamber removed from the cell, and thence back to the lower part of said compartment; heating the said liquid, while in the salt chamber, to expel the chlorin; and e-saturating it with salt in said salt cham- 4;. The herein-described process for the electrolysis of alkali chlorids in a cell containing a horizontal-diaphragm, consisting in passing the anode liquid, in a slightly impoverished condition, from the upper part of the anode compartment of the cell containing the diaphragm to a salt chamber removed from the cell; heating said liquid in the salt chamber to expel-the chlorin; resaturating it therein with salt; returning the re-saturatedliquid to the lower part of said compartment; supplying fresh salt solution regulate the strength and quantity of the liquid returned to said compartment.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

ROLF VAN' HASSELT.

Witnesses:

' I. I. HELSDOR RIX,

THoMAs L. VEsHAL. 

